Wireless Charging Of Electric Vehicles Research Articles

Design of a High Power, LCC-Compensated, Dynamic, Wireless Electric Vehicle Charging System with Improved Misalignment Tolerance

Dynamic wireless power transfer (DWPT) systems are becoming increasingly important for on-the-move electric vehicle (EV) charging solutions, to overcome range anxiety and compensate for the consumed energy while the EV is in motion. In this work, a DWPT EV charging system is proposed to be implemented on a straight road stretch such that it provides the moving EV with energy at a rate of 308 Wh/km. This rate is expected to compensate for the vehicle’s average energy consumption and allow for additional energy storage in the EV battery. The proposed charging system operates at an average power transfer efficiency that is higher than 90% and provides good lateral misalignment tolerance up to ±200 mm. Details of the proposed system’s design are presented in this paper, including EV specifications, inductive link and compensation network design and power electronic circuitry.

Interoperability Improvement for Rectangular Pad and DD Pad of Wireless Electric Vehicle Charging System Based on Adaptive Position Adjustment

Wireless charging for electric vehicles has been investigated in recent years. One of the critical issues of the research is to improve the weak interoperability between two popular charging pads—rectangular pad (RCP) and double-D pad (DDP). This article intends to model the interoperability under pad misalignment and improve it by adjusting the pads’ relative position. First, the variation of interoperability with pad misalignment is analyzed by the flux model. Full output power and high transmission efficiency can be achieved when the two pads are misaligned to a certain distance. Second, the optimal misalignment is obtained by flux calculation and simulation. Third, an adaptive position adjustment method for the transmitting pad based on the variable-step perturbation and observation algorithm is proposed. By searching the maximum dc input current, the optimal position of the transmitting pad can be found. Finally, in the experiment, a 3.3 kW output with 95% coil-coil efficiency is realized when the RCP and DDP interoperate at the optimal position. Compared with the scenario without position adjustment, the improvement of output power and efficiency proves that the proposal can optimize the interoperability between the RCP and DDP.

AC Loss Reduction Through Flux Diverters for Superconducting Wireless Charging Coils at High Frequencies

Wireless power transfer (WPT) for electric vehicles (EVs), also known as wireless charging, is a fast-developing technology with many advantages over conventional cable charging. Novel materials such as high temperature superconductors (HTS) can be used to increase system performance. However, HTS coils have high ac losses at wireless charging frequencies (10-100 kHz) and this is crucial for WPT systems. Flux diverters have been used in the past for dc and low frequency (~50 Hz) superconducting applications but their effectiveness at high frequencies is unexplored. This article investigates the impact of flux diverters on HTS double pancake coils operating at high frequencies up to 85 kHz, commonly used for wireless charging of EVs. Various geometric characteristics of flux diverters are investigated such as air gap between diverter and coil, thickness, and width. A 2-D axisymmetric multilayer model using finite element analysis was used to examine the coil and diverter losses at such frequencies and different load factors (LFs) between 0.1 and 0.8. It is demonstrated that flux diverters are a viable option to reduce the coil losses even at high frequencies and the width of the flux diverter has the biggest impact on the loss reduction. In general, flux diverters are more suitable for applications using high LFs. Lastly, the impact of the diverter in terms of magnetic field distribution above the coil and overall loss distribution in the HTS coil was examined.

Modeling and Analysis of Polarized Couplers under Misalignment for Electric Vehicle Wireless Charging Systems

Wireless power transfer (WPT) is becoming popular increasingly in stationary electric vehicle (EV) charging. Various coil structures were proposed to improve the coupling characteristics, and polarized couplers have been proven to have better performance. Considering the varying spatial scales of transmitting and receiving, coils will alter the mutual inductance, further affecting the output power and transmission efficiency; therefore, it is crucial to calculate the mutual inductance of polarized couplers with variable offset for WPT system design. However, given the complex structure and the various excitation conditions of polarized couplers, the solving process based on the finite element model is time-consuming and resource intensive, therefore it is necessary to develop analytical models of mutual inductance for polarized couplers under misalignment. In this paper, the analytical models of the two commonly used polarized couplers with a Double-D polarized coil (DDP) or a Bipolar polarized coil (BP) on both sides under misalignment along any direction under different excitation conditions are proposed based on dual Fourier transformation. The mutual inductance characteristics of the two polarized couplers under misalignment can be investigated based on the proposed analytical models and finite element models, respectively. The results show that the mutual inductance of BP-BP coupler with in-phase current excitation mode is greater and more stable, and the method based on the analytical model is timesaving. Finally, the prototype of the WPT system with the two polarized couplers has been built, and experiments have also been carried out to verify the accuracy of the analytical models.

A Novel Misalignment Tolerant Magnetic Coupler for Electric Vehicle Wireless Charging

The lateral misalignment for static electric vehicle (EV) wireless charging could be much larger than 100 mm if the parking assistance systems are unavailable. This article proposes a split flat solenoid coupler (SFSC) to significantly extend the lateral misalignment and reduce the copper and ferrite usage. To obtain a good balance among coupling, misalignment tolerance, and cost, an optimization method for SFSC is proposed where the size limitations and ferrite tile specifications are considered. The optimized SFSC is compared with two magnetic couplers recommended in SAE J2954 in terms of coupling coefficient and misalignment tolerance. To eliminate the impact of coil size and make the comparison fair, the quantified misalignment tolerance is introduced. The proposed SFSC provides much better misalignment tolerance than the recommended couplers. A 1000-W prototype is built to show the advantages of the proposed coupler. The output current keeps unchanged when the lateral misalignment is as high as 400 mm. A highest power transfer efficiency, from dc input to dc output, of 89.12% is achieved when the output power is 1000 W.

Variable-Frequency Retuned WPT System for Power Transfer and Efficiency Improvement in Dynamic EV Charging With Fixed Voltage Characteristic

A high efficiency and a constant voltage at the output stage are among the major concerns in wireless charging of dynamic electric vehicles. They are usually achieved by additional converters or asymmetric switching which suffer from high cost and hard switching. To overcome these drawbacks, a variable-frequency retuning approach is proposed in this paper with LCL-Series compensation. As opposed to conventional control methods with resonance frequency as target operating frequency, this approach uses a new optimum frequency which enables ZVS. Also, it minimizes the conduction loss of the inverter switches in a wide range of load and coupling coefficients. In addition, it improves the total system efficiency up to 6% together with an increase in the power transfer capability. Using the proposed method, both sides' currents increases up to 45% depending on the load. To find the optimum frequency in a system without resonant parameter information, an on-line maximum efficiency search method based on Perturb and Observe is employed. Extensive simulation results using PLECS, together with experimental results from a laboratory setup are presented to confirm the effectiveness of the proposed method under varying load and coupling.

Research on Anti-Offset Characteristics of Static Wireless Charging for Electric Vehicles

The static wireless charging of electric vehicles is more convenient than traditional charging methods, but due to man-made parking will cause the coil to shift, which will cause the transmission power of the system to fluctuate and affect the stability of the system. Through the analysis of the traditional doublesided resonant system, it is found that it is more sensitive to the coupling coefficient k and the primary current will increase suddenly when k approaches zero. In order to solve these two problems, this paper compares four different resonance conditions and performs a large number of simulation experiments show that the antioffset performance of the system is the highest when both the primary and secondary sides are designed to be detuned, but a certain efficiency is sacrificed. When the bilateral detuned system is in the range of 2.4 times the coupling coefficient k, then the fluctuation of transmission power is less than 15%, and the maximum transmission efficiency is 58%. It has good anti-offset ability. And when k approaches zero, the primary current will not increase suddenly. The security performance of the system is greatly improved.

Wireless Charging of Electric Vehicle While Driving

Static wireless charging is becoming popular all over the world to charge the electric vehicle (EV). But an EV cannot go too far with a full charge. It will need more batteries to increase its range. Dynamic wireless charging is introduced to EVs to capitally increase their driving range and get rid of heavy batteries. Some modern EVs are getting off this situation. But with Dynamic WPT the need of plug-in charge and static WPT will be removed gradually and the total run of an EV can be limitless. If we charge an EV while it is driven, we do not need to stop or think for charging it again. Eventually, in the future the batteries can be also removed from EVs by applying this method in everywhere. Wireless charging needs two kinds of coils named the transmitter coil and the receiver coil. The receiver coil will collect power from the transmitter coil while going over it in the means of mutual induction. But the variation of distance between two adjacent coils affects the wireless power transfer (WPT). To see the variation in WPT, a system of two Archimedean coils of copper is designed and simulated for vertical and horizontal misalignment in Ansys Maxwell simulation software. The transfer power for 150 mm air gap is 3.74 kW and transfer efficiency are gained up to 92.4%. The charging time is around 1 hour and 39 minutes to fully charge its battery from 0 state for a 150mm air gap for an EV with 6.1 kW power may take. Also, a charging lane is designed for dynamic charging. Then the power transfer is calculated from mutual inductance when the EV is driven on a charging lane. From the load power, it can be calculated how further an EV can go with this extra power.

电动汽车无线充电有序管理策略的研究

电动汽车无线充电有序管理策略的研究

Solar self-powered wireless charging pavement—a review on photovoltaic pavement and wireless charging for electric vehicles

The world today is facing an energy crisis, which has promoted the development and utilization of renewable energy, of which solar energy has the greatest potential.

Simultaneous Metal Object Detection and Coil Alignment for Wireless EV Chargers Using Planar Coil Array

For the commercialization of wireless electric vehicle (EV) chargers, the metal object detection and coil alignment are needed for the safe and efficient operation of chargers. This paper proposes a dual-purpose method for the simultaneous metal object detection and coil alignment using a planar coil array before the start of wireless EV charging. Magnetic induction tomography is adopted to reconstruct the images of metal objects and the location of the objects is calculated using the image processing algorithms. The receiving coil in the EV is visualized using the induced voltage map from the coil array and the coil position is computed using characteristic points of the map. Firstly, the structure of the coil array is optimized using the finite element model (FEM) and 4×4 coil elements are used. Then the FEM simulation is conducted for the feasibility study of the proposed method. Finally, an experimental setup of the wireless charging is designed for further verification. For the metal object detection, eight experimental cases prove that the proposed method is able to detect and visualize metal objects with different numbers and different shapes. In addition, the maximum location error for all metal objects is 6.27 mm. For the coil alignment, the location error of the receiving coil is less than 2 cm. The proposed method can help to remove metal objects and assist the driver during the parking, which meets the requirement for the wireless EV charging.

Wireless power charging and identification of theft electric vehicle using Block chain technology

Vehicles have become an indispensable part of every human’s life. Almost, every work depends on vehicle for transportation. Without the vehicle our work would be crucial. Though a vehicle have many benefits, it also creates a major threat for the environment by its pollution. Additionally, the existing system fails to charge the Electric Vehicle (EV) system as there is no separate charging system. This can be implemented by our proposed system wireless power charging technology using inductive coupling method. Consequently, existing system also fails to identify the theft EV in an efficient manner. This issues can be solved by using a mobile application with vehicle information. The application maintains the blockchain server which continuously monitors theft Electric Vehicle by sending, vehicle information to all rechargeable stations. In case, the theft Electric Vehicle enters the charging station the information is passed to the authorized person of the Electric Vehicle. As a result the proposed system integrates Wireless charging and anti-theft vehicle in an efficient way when compared with the existing system.

Experimental Study of Radiated Magnetic Field from Electric Vehicle Wireless Charging System

Wireless charging is an attractive option of energy replenishment for electric vehicles (EVs) as it does not require direct electrical contact to the EVs. However, the radiated magnetic field from the EV wireless charging system can be an electromagnetic compatibility (EMC) concern nearby electrical and electronic devices. This paper investigates the influence of the power level, the clearance, and offset between coils on the radiated magnetic field emitted from the wireless charging system. The experimental study shows that these variable parameters can affect the radiated magnetic field level and the field distribution, which provides valuable input for standardization of the test setup and working condition of the EV wireless charging system.

An Efficient PCB Based Magnetic Coupler Design for Electric Vehicle Wireless Charging

This paper proposes an efficient Printed Circuit Board (PCB) design of magnetic couplers for electric vehicle (EV) wireless power transfer (WPT) system. Since a WPT system operates at high frequency, Litz wire typically is used that can overcome high AC resistance, and improve overall efficiency. In EV wireless charging applications, the power level of the system is high, and therefore the magnetic pad size and copper cross-section of the Litz wire used in the magnetic couplers are large which increases the cost and weight. Besides, building the magnetic couplers using Litz wire requires excessive labor work, which causes fabrication errors. Replacing the Litz wire with PCB-based coils raises design and efficiency challenges. A new approach for designing the PCB-based magnetic couplers for high-power EV wireless charging applications is proposed to address the challenges associated with the PCB designs. In the proposed design, the efficiency of the PCB-based design is close to the Litz wire-based design. Moreover, machine assembly replaces the labor work and the magnetic coupler can be implemented with lower fabrication error, weight, and manufacturing cost. In this paper, a 3.3 kW PCB-based WPT system is designed, compared experimentally with the Litz wire setup which achieved a competitive efficiency profile.

A Fast Construction Method of Resonance Compensation Network for Electric Vehicle Wireless Charging System

When constructing an electric vehicle (EV) wireless charging system, limited by manufacturing technology and measurement errors, the capacitance and inductance in the impedance matching network will inevitably produce parameter deviations, which will cause tuning difficulties and even burn the power supply. In order to solve these problems, this article proposes a fast and accurate tuning technique based on a double-sided L3C compensation network with a capacitor matrix. The tuning method derived from theoretical analysis can be summarized as: tuning capacitor can achieve fast matching; fine adjusting the equivalent inductance can achieve precise matching and power zero-voltage switching. After resonance matching, the capacitors on the capacitor matrix can be removed and welded together, and an inductor can be used instead of equivalent inductance, so the technology is low cost, fast, and safe. In order to verify the tuning method, a 3-kW EV wireless charging system was developed. Experimental results show that the proposed method makes the system resonate rapidly and maintain stability, and the inverter is also easy to implement zero-voltage switching.

RESEARCH ON SHIELDING AND ELECTROMAGNETIC EXPOSURE SAFETY OF AN ELECTRIC VEHICLE WIRELESS CHARGING COIL

RESEARCH ON SHIELDING AND ELECTROMAGNETIC EXPOSURE SAFETY OF AN ELECTRIC VEHICLE WIRELESS CHARGING COIL

A Technology Trend and Analysis of Electric Vehicle Wireless Charging System

A Technology Trend and Analysis of Electric Vehicle Wireless Charging System

Strategic network design and analysis for in-motion wireless charging of electric vehicles

We address a network design problem arising in the deployment of wireless charging stations (WCSs) within an urban transportation network. It is widely acknowledged that, despite the availability of EV conventional charging facilities, the relatively short driving range of EVs (due to low energy density of the batteries) and the long battery charging times (collectively leading to a phenomenon known as “range anxiety”) remain the major factors that hamper EV adoption. Thus, in this research, we study a cost-effective WCS deployment network design that facilitates EV adoption by alleviating these two major anti-adoption factors.We consider the problem from the perspective of a city as the decision maker whose aim is to satisfy the charging demands of all EVs in its urban traffic network at the minimum cost including installation and charging costs. For this purpose, we suggest a new mathematical model to strategically deploy WCSs in the network in such a way that no EV runs out of energy before reaching its destination. To solve the proposed model, we devise a combined combinatorial-classical Benders Decomposition approach and further enhance its efficiency via employing surrogate constraints and an upper bound heuristic. We present computational results illustrating the algorithmic efficiency of our approach as well as an analysis of the effect of varying system and new technology related parameters (i.e., product design) on the resulting network design based on a case study with urban network data from Chicago, IL.

Load Balancing of a Modular Multilevel Grid-Interface Converter for Transformer-Less Large-Scale Wireless Electric Vehicle Charging Infrastructure

This article analyzes the requirements for load balancing of a new transformer-less grid-interface topology for large-scale electric vehicle (EV) charging infrastructures. The proposed configuration utilizes a modular multilevel converter (MMC) to supply wireless EV chargers from each module. The inherent galvanic isolation provided by wireless inductive power transfer and the scalability of the MMC topology enable transformer-less connection to medium voltage (MV) distribution grids. This can reduce the footprint and copper volume of the internal power distribution for the parking infrastructure. The load distribution within the MMC topology depends on the location and power requirements of each EV to be charged. Requirements for load balancing by controlling the internal circulating currents of the proposed topology when supplying unevenly distributed loads are derived. It is also demonstrated how a second harmonic component of the circulating currents can be utilized to ensure balancing capability within each MMC arm, and how its required amplitude depends on the load distribution. The theoretical analysis and the performance of a corresponding control strategy are first verified by time-domain simulations of a large-scale infrastructure. Experimental results from a small-scale prototype based on an MMC where each arm has 12 modules with individual controllable loads are presented.

Method for metal foreign object detection in wireless charging system of electric vehicle

Purpose This study aims to solve the problem of the existing metal foreign object (MFO) detecting systems, which are not sensitive to the small size MFO in wireless charging region of electric vehicle (EV) because of the extremely complex signal noise in the process of wireless charging of EV. Design/methodology/approach A method for MFO detection based on the principle that MFOs can cause mistuned resonance of detection coil resonant circuit is proposed. The general scheme of detecting system is proposed. The design method for detection coils which is effective to small MFOs detection in large-area region of wireless charging of EV is presented. The design of time-sharing driving circuit and amplifying circuit of high frequency exciting signal for detection coils is introduced. The design scheme of signal processing circuit (including filter and rectifier) of detection coil terminal voltage is also proposed. Findings The influence of exciting frequency of detection coils on detecting sensitivity and the anti-noise feature of system are analyzed according to the experiment results. Originality/value The experiment of MFO detection indicates that the proposed method can effectively detect the coin-sized small MFO in the process of wireless charging of EV.